Researchers working with mousepox virus
have created a recombinant virus capable of escaping the effects of prior immunization with vaccinia virus (22).
In the first study, researchers from Australia inserted the mouse IL-4 gene into the mousepox virus
with the aim of sterilizing the mice as a means of pest control.
The possibility that researchers could genetically manipulate the natural enemies of non-native species to kill them faster and better, thus protecting the "natural" environment, attracted public notice in 2001, when a team of virologists, seeking to control non-native rodents in Australia, announced that it had had added an interleukin-4 gene, which suppresses the immune response, to ectromelia or mousepox virus
For example, modified mousepox virus
with an interleukin-4 gene was shown to induce unexpected lethality in mice usually protected from mousepox via vaccination (6).